手機註冊發送驗證碼倒計時

()這裡用的是input做的點擊發送驗證碼
<input type="number" class="input" name="mobile" placeholder="手機號" style="border: none"

<input class="hui_kuang"style="width: 30%;text-align: center;height: 42px"onclick="setTime(this)" value='獲取驗證碼'>
<script>
　　

//頁面初始化獲取倒計時數字（避免在倒計時時用戶刷新瀏覽器導致倒計時歸零）
    var $getCodeInput = $(".hui_kuang");
    var sessionCountdown = sessionStorage.getItem("countdown");
    if (!sessionCountdown) {
        $(".hui_kuang").val("獲取驗證碼")
    } else {
        $(".hui_kuang").val("重新發送(" + sessionCountdown + ")");
        setCode($getCodeInput, sessionCountdown);
    }
    //獲取驗證碼
    function setTime() {
        var remobile = $("#registForm input[name='mobile']").val();
        if (!remobile) {
            alert("請輸入手機號碼")
            return;

        }
        if (!(/^1[3|4|5|8][0-9]\d{4,8}$/.test(remobile))) {
            alert("請輸入有效的手機號碼")
            return;
        } else {
            setCode($getCodeInput, 60);
        }

    }
    //發送驗證碼倒計時
    function setCode($getCodeInput, countdown) {
        if (countdown == 0) {
            $getCodeInput.attr('disabled', false);
//            $getCodeInput.removeAttribute("disabled");
            $getCodeInput.val("獲取驗證碼");
            sessionStorage.removeItem("countdown");
            return;
        } else {
            $getCodeInput.attr('disabled', true);
            $getCodeInput.val("重新發送(" + countdown + ")");
            countdown--;
        }
        sessionStorage.setItem("countdown", countdown);
        window.setTimeout(function () {
            setCode($getCodeInput, countdown);
        }, 1000);
    }

</script>